The goals of the proposed project are to a) elucidate those molecular mechanisms involved in ATP synthesis in normal liver cells; b) to understand how ATP synthesis is regulated in liver cells; and c) to undersand why many rapidly growing cancer cells have an abnormal energy metabolism. To meet the first two objectives we are working with the mitochondrial ATP synthetase complex (H+-translocating ATPase) and its ATPase peptide inhibitor. We propose to study the F1-component of the ATP synthetase complex in great detail in order to ascertain both its mechanism of action and its structure. Active site studies using covalent labelling agents and X-ray crystallographic studies have been initiated and will be vigorously continued. In order to meet the second objective we are studying mitochondrially-bound hexokinase of cancer cells. This enzyme has been shown in our laboratory to be responsible, at least in part, for the high glucose consumption rate of rapidly growing cancer cells. We propose to study in detail the molecular, regulatory, and membrane binding properties of mitochondrially-bound hexokinase, and ascertain the extent to which it is characteristic of animal tumors. The proposed studies are both necessary and fundamental to elucidating and understanding the complex mechanisms underlying energy metabolism of normal and cancer cells.